Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Not designated as hedges | Prime Lending
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	$ 47,267	$ (783)	$ 67,143	$ 17,405
Not designated as hedges | Hilltop Broker-Dealers
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	20,149	12,581	12,008	10,774
Not designated as hedges | PlainsCapital (the Bank)
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	0	$ (85)	(135)	$ (146)
IRLCs | Not designated as hedges
Derivative financial instruments
Notional Amount	2,782,720		2,782,720		$ 914,526
Estimated Fair Value	101,210		101,210		18,222
Customer-based written options | Not designated as hedges
Derivative financial instruments
Notional Amount					31,200
Customer-based purchased options | Not designated as hedges
Derivative financial instruments
Notional Amount					31,200
Commitments to Purchase MBSs | Not designated as hedges
Derivative financial instruments
Notional Amount	2,056,173		2,056,173		3,346,946
Estimated Fair Value	15,779		15,779		3,321
Commitments to Sell MBSs | Not designated as hedges
Derivative financial instruments
Notional Amount	5,695,995		5,695,995		5,988,198
Estimated Fair Value	(20,613)		(20,613)		(5,904)
Commitments to Sell MBSs | Not designated as hedges | Prime Lending
Derivative financial instruments
Cash collateral advanced to offset net derivative liability	21,100		21,100		4,500
Interest rate swaps | Not designated as hedges
Derivative financial instruments
Notional Amount	47,399		47,399		15,012
Estimated Fair Value	(2,147)		(2,147)		(178)
Interest rate swaps | Cash Flow Hedging | Designated as hedges
Derivative financial instruments
Notional Amount	105,000		105,000		50,000
Estimated Fair Value	(4,092)		(4,092)		528
U.S. Treasury bond futures and options | Not designated as hedges
Derivative financial instruments
Notional Amount	113,100		113,100		283,500
Eurodollar futures | Not designated as hedges
Derivative financial instruments
Notional Amount	14,000		14,000		934,000
Treasury bond futures and options and Eurodollar futures | Not designated as hedges | PrimeLending and Hilltop Broker-Dealers
Derivative financial instruments
Cash collateral advanced to offset net derivative liability	$ 1,400		$ 1,400		$ 3,700